The
ethical principle of Double Effect is used to justify medical treatment
designed to relieve suffering where death is its unintended (though foreseen)
consequence. It comes from "the rule of double effect" developed by Roman
Catholic moral theologians in the Middle Ages as a response to situations
requiring actions in which it is impossible to avoid all harmful consequences.
The rule makes intention in the mind of the doctor a crucial factor in judging
the moral correctness of the doctor's action because of the Roman Catholic
teaching that it is never permissible to "intend" the death of an
"innocent person". An innocent person is one who has not forfeited the right
to life by the way he or she behaves, eg, by threatening or taking the lives
of others.

There is controversy as to whether or not the consequence can be said to
be unintended if it can be foreseen. Whatever the moral significance, intention
in the mind of the physician is a dubious criterion for the framing of public
policy. If life is deliberately shortened or ended in this way in the guise
of symptom relief, it may be classed as "indirect euthanasia."
This appears to be resorted to not infrequently by doctors acting from compassion

For
clinicians and others who believe in an absolute prohibition against actions
that intentionally cause death, the rule of double effect may be useful
as a way of justifying adequate pain relief and other palliative measures
for dying patients. But the rule is not a necessary means to that important
end. Furthermore, the rule's absolute prohibitions, unrealistic characterization
of physicians' intentions, and failure to account for patients' wishes make
it problematic in many circumstances. In keeping with the traditions of
medicine and broader society, we believe that physicians' care of their
dying patients is properly guided and justified by patients' informed consent,
the degree of suffering, and the absence of less harmful alternatives to
the treatment contemplated.

According
to the traditional doctrine of double effect it is permissible to act in
ways which it is foreseen will have bad consequences provided only that

(a) this occurs as a side effect (or indirectly) to the achievement
of the act which is directly aimed at or intended; (b) the act directly
aimed at is itself morally good or, at least, morally neutral; (c) the
good effect is not achieved by way of the bad, that is, the bad must
not be a means to the good; and (d) the bad consequences must not be
so serious as to outweigh the good effect.

In
line with the doctrine of double effect it is, for example, held to be permissible
to alleviate pain by administering drugs like morphine which it is foreseen
will shorten life, whereas to give an overdose or injection with the direct
intention of terminating a patients life (whether at her request or
not) is considered morally indefensible. This is not the appropriate forum
to give full consideration to this doctrine. However, there is one vital
criticism to be made of the doctrine in relation to the issue of voluntary
euthanasia. With that point made we will be able to turn to the more general
question of the moral permissibility of intentional killing.

The
criticism of the relevance of the doctrine of double effect to any critique
of voluntary euthanasia is simply this: the doctrine can only be relevant
where a persons death is an evil or, to put it another way, a harm.
Sometimes "harm" is understood simply as damage to a persons
interest whether consented to or not. At other times it is more strictly
understood as wrongfully inflicted damage. On the latter understanding consent
becomes crucial. Unless paternalistic interference is judged to be appropriate
the giving of consent removes any suggestion of wrongfulness. So, if the
death of a person who wishes to die is not harmful (because from that persons
standpoint it is, in fact, beneficial), the doctrine of double effect can
have no relevance to the debate about the permissibility of voluntary euthanasia.